294 



DE. G. H. rOWLEE — BISCATAN PLANKTON: 



The specimens at 0, 25, and 50 fathoms were too few to give any indication of diurnal 

 oscillation or of reaction to rain. But 



At 75 fathoms the average catch was 35'00 specimens by day, 



73-85 „ night, 



„ 866 „ day, 



100 





20-75 



night, 



showing a rise in the population at both horizons by night, and a plurimum at 

 75 fathoms for both day and night. 



CONCHOECIA SPINIFERA, Claus. 



15 per cent, of 13 hauls, with 0-46 ~1 



out of 



10 

 17 



7 

 3 

 3 

 3 

 3 

 4 

 5 



average 

 2-30 )> specimens 

 2'00 J per hour haul. 



51 



0-14 

 1-00 

 0-66 

 1-66 

 0-33 

 0-40 

 0-08 J 



> 



average 

 specimens 



per 



100 fathom 



haul. 



All the epiplanktouic specimens were taken by night, which points to a nocturnal 

 rise from the upper mesoplankton. The species was so scarce at aU depths that it is 

 doubtful where its plurimum (if any) was to be found; perhaps somewhere between 

 400 and 150 fathoms. 



CoNCHOECIA SPINIROSTRIS, ClaUS. 

 = C. porrectu, Claus. 



The total number of specimens is so small that to reduce them to the usual " average 

 specimens per hour haul " would be rather a farce. 



At 

 25 

 50 



75 

 100 J 



fathoms 

 this species 

 occurred in 



1 out of 13 hauls, with by day + 1 by night = 1 specimen. 

 1 „ 12 „ 1 „ +0 „ =1 



-! 5 „ 13 „ 2 „ +5 „ =7specimens. 



4 „ 10 „ 4 „ +3 „ =7 



l5 „ 17 „ 6 „ +1 „ =7 



The table * shows the rarity at all depths. As there were so few specimens in the 

 epiplankton, it is not surprising that none were captured in the mesoplankton. 



* Actual numbers ; not multiplied by a time-factor. 



